Frontiers in Chemistry (Sep 2022)

Multiple resonance type thermally activated delayed fluorescence by dibenzo [1,4] azaborine derivatives

  • Jaehyun Bae,
  • Jaehyun Bae,
  • Mika Sakai,
  • Youichi Tsuchiya,
  • Naoki Ando,
  • Xian-Kai Chen,
  • Thanh Ba Nguyen,
  • Thanh Ba Nguyen,
  • Chin-Yiu Chan,
  • Yi-Ting Lee,
  • Morgan Auffray,
  • Hajime Nakanotani,
  • Hajime Nakanotani,
  • Shigehiro Yamaguchi,
  • Shigehiro Yamaguchi,
  • Shigehiro Yamaguchi,
  • Chihaya Adachi,
  • Chihaya Adachi,
  • Chihaya Adachi

DOI
https://doi.org/10.3389/fchem.2022.990918
Journal volume & issue
Vol. 10

Abstract

Read online

We studied the photophysical and electroluminescent (EL) characteristics of a series of azaborine derivatives having a pair of boron and nitrogen aimed at the multi-resonance (MR) effect. The computational study with the STEOM-DLPNO-CCSD method clarified that the combination of a BN ring-fusion and a terminal carbazole enhanced the MR effect and spin-orbit coupling matrix element (SOCME), simultaneously. Also, we clarified that the second triplet excited state (T2) plays an important role in efficient MR-based thermally activated delayed fluorescence (TADF). Furthermore, we obtained a blue–violet OLED with an external EL quantum efficiency (EQE) of 9.1%, implying the presence of a pronounced nonradiative decay path from the lowest triplet excited state (T1).

Keywords